Paul Grice is the philosopher who introduced the idea that language is based
on a form of cooperation among speakers.
People always choose the speech acts that achieve the goal with
minimum cost and highest efficiency.
Grice was influential in emphasizing the linguistic interplay between the
speaker, who wants to be understood and cause an action, and the listener.
This goes beyond syntax and semantics. A sentence has a timeless meaning,
but also an occasional meaning: what the speaker meant to achieve when s/he
uttered it. Language has meaning to the extent that some conventions hold
within the linguistic community. Those conventions help the speaker achieve
his/her goal. The participants of a conversation cooperate in saying only
what makes sense in that circumstance.
The significance of an utterance includes both what is said (the explicit)
and what is implicated (the implicit). Grice therefore distinguishes between
the proposition expressed from the proposition implied, or the "implicature".
Implicatures exhibit properties of cancellability (the implicature can be
removed without creating a contradiction)
and calculability (an implicature can always be derived by reasoning under the
assumption that the speaker is observing pragmatic principles).
A particularized implicature is one that is such in virtue of the context.
A generalized implicature is independent of the context.
Grice's four maxims summarize those conventions. They help the speaker
say more than it says through implicatures which can be implied by the
utterance. Conventional implicatures are determined by linguistic constructions
in the utterance. Conversational implicatures follow from maxims
of truthfulness, informativeness, relevance and clarity that speakers are
assume to observe. Conversational implicatures can be discovered through an
inferential process: the hearer can deduct that the speaker meant something
besides what he said by the fact that what he said led the hearer believe
in something and the speaker did not do anything to stop him from thinking it.
The maxims are: provide as much information as needed in the context, but no
more than needed (quantity), tell true information (quality), say only things
that are relevant to the context (relation), avoid ambiguity as much as
possible (manner).